Oh relax. Understand this simple thing: You cannot prove that your god exists but worship him through faith. Faith which only you can see and understand. The rest is made up assumptions.
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Some numbers:
(1) Christianity: About 2.3 billion followers.
(2) Islam: About 1.5 billion followers.
(3) Judaism: About 14 million followers.
Looks like just shy of 4 billion people have this faith you speak of.
How do you know another's faith.... it's a personal thing. Faith is your own thoughts and beliefs.
Yes you can share a similar faith with others, which are shown by the numbers above, but your own faith is personal to you.
Hence my comments above....
For humanity, that is why problems arise, because each one's faith is imposed on others. If it would be because you say that faith for everyone is purely personal, there would be fewer problems on a religious basis.